It is often difficult for farmers to identify diseases quickly enough to protect their crops and those on neighboring farms．Now，some farmers are using a simple device directly in the field to find viruses before they spread．
In Tanzania，several viruses are a threat to cassava crops．Farmers struggle to identify the diseases in an urgent effort to avoid severe crop damage．The disease identification process is often difficult when farmers are acting on their own．If they do not know what is attacking their crops，they cannot decide the best way to fight the disease．A device from British technology company Oxford Nanopore is changing that．The device
extracts deoxyribonucleic acid，better known as DNA，from plants．DNA is the carrier of genetic information in nearly all living things．The device helps farmers identify what is harming their crops so they can change to more resistant crops．
Laura Boykin is with the University of Western Australia and also works with the Cassava Virus Action Project．She brought the device to a Tanzanian farm owned by Asha Mohamed．She said， "We are here collecting leaf punches from infected material to test，to do a DNA extraction and then start sequencing （排序） in the field．" The testing identified a number of viruses in the cassava fields near Mohamed's farm．The process also discovered that plants considered resistant to disease had a very low viral level．Once the viruses were identified，Asha Mohamed was given two kinds of seeds that are resistant to the diseases．
In another case，DNA was collected from a pawpaw tree farm in Kenya．With that test，the technology was able to identify diseases affecting Naomi Mumo's crops．Naomi Mumo said， "All my pawpaw were affected by a disease，and I didn't know what kind of disease it was．But now，I have people who have identified the disease using new technology，and within a very short time．So I'm very happy．"
The speed at which farmers identify diseases can mean the difference between the success or failure on large areas of crop land．Now，the use of such simple and easily transportable DNA sequencing devices is making that possible．
（1）What's the main idea of the whole passage？
C
C
A．Farmers In Tanzania struggle to identify the diseases in their crops
B．How Laura Boykin helped Asha Mohamed to identify the viruses．
C．DNA sequencing device helps farmers to find viruses and identify the diseases in their crops quickly．
D．A DNA sequencing device helps farmers to identify the diseases and keep healthy．
（2）Which of the following best explains "extracts" underlined in paragraph 2？
D
D
A．produces
B．creates
C．refuses
D．gets
（3）We can infer from the passage that Naomi Mumo is
B
B
with the DNA sequencing device．
A．relaxed
B．satisfied
C．disappointed
D．a(chǎn)nnoyed
（4）Which of the following is not true according to the passage？
C
C
A．Farmers often have difficulty in identifying diseases in their crops quickly by themselves．
B．DNA carries genetic information in nearly all living things．
C．Both Asha Mohamed and Naomi Mumo are farmers in Tanzania．
D．If farmers can identify diseases in their crops quickly，they can protect their crops and succeed on large areas of crop land．
